A sensitive and versatile analytical system, capable of identifying both large and small molecules and determining their molecular structure, is required to address the complex mixtures of molecules found in many types of chemical and biological problems. Mass spectrometry is a technique of obtaining information regarding the mass of specimen molecules by ionizing the molecules into charged particles for identifying the species of the molecule. In high performance mass spectrometry, it is desired to obtain the best possible accuracy in determining the composition of the sample or molecule that is being measured.
An ITMS (Ion Trap Mass Spectrometer) is a potentially powerful tool for the analysis of biopolymers. An ITSM utilizes electrostatic fields to trap ions in a small volume. Advantages of an ITSM include its compact size and its ability to trap and accumulate ions to increase the signal-to-noise ratio and sensitivity of a measurement. The performance of the ITSM is generally dependent on radio frequency (RF) voltage and frequency.
Miniature mass spectrometers utilized in non-laboratory and harsh environments are of interest for continuous on-line and other monitoring tasks. For miniaturized ion traps, such as chip-scale ion trap arrays fabricated on a silicon wafer, the required RF frequency may be 100 MHz to 1000 MHz, while the voltage amplitude may be maintained at several hundred volts. The large voltage swing at a high frequency presents a difficulty in coupling and transmitting the RF power to distributed ion traps on the chip due to large parasitic losses. Additionally, the drive frequency of the ion trap must be increased to detect the low mass ions and maintain resolution as the ion trap dimensions are decreased. Therefore, the trapping of ions in a micro scale trap is difficult. Furthermore, it can be nearly impossible to construct large arrays of a small ITMS in a chip-scale size for mass trapping of ions.
Based on the foregoing, it is believed that a need exists for an improved chip-scale ion-trap mass spectrometer. A need also exists for an improved RF source in proximity with the ITMS, which can be a monolithic photodiode array as described in greater detail herein.